The New York Stock Exchange (NYSE) reopened for trading after a three-hour shutdown on 8 July due to a "technical glitch", but rumours are rife that the Anonymous group might have played a role.
Hours before the exchange closed down, one of the hacker Anonymous groups most popular accounts warned of potential problems on the Wall Street.
Trading came to a halt on the New York Stock Exchange floor on 8 July with authorities assuring that there was no suspected cyberattack.
At roughly 11.30am New York time, the NYSE said: "NYSE/NYSE MKT has temporarily suspended trading in all symbols. All open orders will be cancelled."
"There is no indication that there are malicious actors involved," confirmed White House Press Secretary Josh Earnest, reported CNBC.
FBI continues to "monitor the situation", however "no further law enforcement action is needed at this time."
Meanwhile, NYSE president Thomas Farley told CNBC: "We identified the issue and we have that addressed. Our system is more than just software, the network connectivity, the various external internal sources, and the actual hardware.
"It's not a good day and I don't feel good for our customers who continue to deal with the fallout. I wanted my team to take their time and get it right, be open for the close."
Farley said operations will resume at 2:45-3pm local time.